ISDN
(is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires.)
PRI
(is a telecommunications standard for carrying multiple DS0 voice and data transmissions between two physical locations.)
DS0
(is a basic digital signaling rate of 64 kbit/s, corresponding to the capacity of one voice-frequency-equivalent channel.)
CPE
(is any terminal and associated equipment and inside wiring located at a subscriber's premises and connected with a carrier's telecommunication channel(s).)
DCME
(Digital Circuit Multiplication Equipment (DCME) is a type of voice compression equipment that is installed at either end of a long-distance link (typically satellite or submarine).)
SNR
(Signal-to-noise ratio (often abbreviated SNR or S/N) is an electrical engineering concept defined as the ratio of a signal power to the noise power corrupting the signal.)